Electric switch



Aug- Q, 1940. w, BUTLER 2210,7393

ELECTRIC SWITCH Filed March 25, 1939 Z 5 v 5 5 i F I 5 5 a 4 Inverfitor. William Lawrence Butler;

\ by n M IS Attorney.

Patented Aug. 6, 1940 2,210,793 I nrnormo swrrcn William Lawrence Butler, Schenectady, N. Y., assignor to GeneorarlkElectflc Company, a. corporation of New Y Application 25, 1939, Serial N0. 264,157

14 Claims. (Cl. 200-153) My invention relates to electric switches, more particularly to limit switches having an element operable to the circuit opening and circuit closing positions, and has for an object the provision of a simple, reliable and improved switch of this character.

In carrying my invention into eiiect in oneform thereof, I have provided a cam-operated limit switch enclosed in a suitable casing. A ll) demountable bearingplate is secured to the easing :for supporting the entire movable operating and switching structure, thereby permitting easy assembly and removal of these parts as a unit from the casing. A fixed switching element is 5 supported in the casing, and a cooperating movable switching-element is pivotally mounted on the bearing plate. For operating the movable switching element in accordance with the movement of an actuating handle positioned outside 20 the casing, a cam means is provided, and provision for limited over-travel of this means is made. In addition, a simple spring arrangement is provided for biasing the operating means to and for return to an initial position, while serving simultaneously to bias the movable switching element to its initial position. A contact structure is carried by the movable switching element and is especially adapted for a wiping engagement with the contacts of the fixed switching element.

For a further and more complete understanda ing of my-invention, reference should now be had to the following specification and to the accompanying drawing of which Fig. l is an ele- 33 vational view of a casing embodying the switch of my invention and showing various positions of the exteriorly disposed actuating handle; Fig. 2 is a sectional view taken along the lines 2-2 of Fig. 1 looking in the direction of the ar- 41) rows; Fig. 3 is an elevational view similar to Fig. 1 with the bearing plate and the cover plate of the casing removed and showing the switch and Fig. 5 is an exploded view in perspective of the details of Figs. 1 to4. Referring now to the drawing, I have shown my invention in one form as a limit switch having a suitable enclosing casing l0 provided at the 50 front thereof with a cover plate ll secured by the screws l2. The casing I0 is provided with a conduit receiving opening l3 through which the controlled connections (not shown) may enter the casing. Preferably, the cover plate It is 5 mounted on the front side of the casing It so that the switch may be wired from the front side.

Actuating means for the switch, shown as the rotatably mounted actuating shaft M, extends through the front'side of the casing. The ac- 5 tuating shaft i8 is mounted for rotation in the rear wall of the casing it and is journaled in a demountable bearing plate I 5 arranged in the front side of the casing. The screws it serve to secure the bearing plate IE on to the casing it, 10 the front side of the bearing plate in being flush with the front surface of the cover plate it so that a continuous smooth surface is presented at the front of the casing.

0n the extension of the shaft M, which pro- 115 jects through the front side of the casing, is mounted a switch-operating lever arm i7. Suitable fastening means for the lever arm ii is provided at its secured end, such as a bifurcated portion 08 and the nut'and bolt is. On the free end of the lever arm ii, a conventional roller 2! is mounted for co-operation with the machine part to be controlled. The normal position of the lever arm is shown in full lines in Fig. 1, its operated position being shown in dotted lines. Simply by loosening the nut-and bolt is, the lever arm it may readily be adjusted to any desired normal position by rotation on the shaft M. I

The switch is provided with a fixed switching element which co-operates with a movable switching element in a manner explained more fully hereinafter to perform the switching function. For example, the fixed switching element comprises a pair of contacts 2| to be bridged by the movable switching element in the normal position and a pair of contacts 22 to be bridged by the movable switching element in the operated position, suitably secured on an insulated support 23 fastened on the back wall of the casing 40 ID by the screws 24. In this manner, the easing serves as a support for the fixed element of the switch, i. e., the normally closed contacts 2| and the normally open contacts 22. The movable switching element comprises, for ex-. ample, the bridging contacts 25 and 26 which are disposed adjacent the pairs of fixed contacts 2| and 22 for arcuate movement therebetween, the bridging contact 25 coacting and normally in engagement with the fixed contacts 2|, and the bridging contacts 26 coacting and normally in disengagement with the fixed contacts 22.

The switch is also provided with a pivoted op.- erating element which serves as a main support and operating means for the movable switching the movable contacts 25 on a' pin 28 the spirit and scope wish to be limited to element. Preferably, this operating element comprises a pivotally mounted operating arm 21 whichmay be made of a suitable insulating material, such as a plasticizable phenolic condensation product, the operating arm'21 being pivoted mounted on the bearing plate B5. The operating element 21 has an extending portion, for example, the post 29, which extends transversely of and substantially perpendicularly to the line of movement of the movable contacts 25 and 25. As shown, the post 29 comprises an insert molded into the member 21 or it may be a projection formed integrally with the member 21. Confining means are provided on the post 23 to hold a helical spring 30 thereon, this means being here illustrated as a collar 3| on the lower end of the post and the main supporting element 21. The helical spring encircles the post 29 and is held under compression between the confining means, auxiliary supporting means for the movable contacts being interposed between the collar 3| and the adjacent end of the spring 29 as described hereinbelow.

The auxiliary supporting means for the movable contacts is carried by the post 29 to afiord means whereby a good wiping engagement of these contacts with their respective'fixed contacts is secured. This supporting means comprises the elements 32 and 33, which are identical, each of them carrying one pair of movable contacts thereon. The element 32, for instance,.has an upper portion 34 lying on a plane substantially perpendicular tothe axial line of the post 29 or the spring 30 and provided with suitable mounting means, such as an open-ended key-hole slot or aperture 35, for receiving the post 29 therein, the portion 33 of the element 32 being disposed between the lower end of the spring 30 and the collar 3|. The lower portion 36 of the element 32 may have any suitable. configuration whereby are supported in spaced relation to the plane of the upper portion 35 for providing a leverage which will serve to rock or roll the upper portion 35 on the collar 3| when the contacts engage and disengage. Preferably, the lower portion 35 of the element 32 lies in a plane transverse to the line of movement of the movable contacts and substantially parallel to the post 29.

As seen in Fig. 3, with the switch in its normal position, the contacts 2| and 25 are biased into engagement, the auxiliary support 32 being tilted slightly on the edge of the collar 3|. When the contacts 2| and 25 are out of engagement, the upper portion 36 of the support 32 lies fiat along the collar 3|. At the moment of engagement,

the contact 25 presses against the contact 2|;

causing the support 32 to tilt andsimultaneously slide the contact 25 downwardly across the contact 2|, providing a good wiping engagement of these contacts. Upon disengagement, tact 25 slides upwardly and then away from the contact 2|.

As seen in Figs. 3 and two elements 32 and 33 each supported on the post 29, but facing in opposite directions. Since a single element of this character might be provided to support all of the movable contacts or a pair of posts might be provided, each post su porting a single element, without departing from of my invention, I do not the exact contact structure 4, I have provided the herein described.

The operating element 21 referred to above is rotated about its pivot point 28 by a suitable spaced apart the conwise rotation of the cam operating member, preferably a cam 31 secured on a squared portion of the actuating shaft i i.

To minimize the friction in the camming relaported bythe operating arm 21 in engagement with the outer edge of the cam, 31. Limiting means'are provided to determine the extent of angular movement ofthe cam 31, and this means comprises av stop 39 disposed between a pair of projections 30 and 4| on the upper peripheral edge of, the cam 31. The stop 39,

preferably cast integrally with the bearing plate the upper portion of the i5, is shown secured to bearing plate by means of a screw 92.

It will be observed that I have provided spring means for biasing the cam 31 and the operating element 21, respectively, to their normal positions as shown in Fig. 3. The spring means is ar ranged to be tensioned by the movement of the cam 31 from its normal position to the operated position, shown in Fig. 4, for biasing the operating element 21 and the cam for a quick return from the operated position to the normal position,

when the actuating handle I1 is released. A'

single helical spring 93 comprises the spring means above, and it encircles the inner end of the shaft M between the cam 31 and the rear wall of the casing I0. As shown in Figs. 3 and 4, the end of the spring engages a projection 64 thereon for biasing the cam in a clockwise direction, the rotation of the cam in this direction being limited by the stop 39 and the co-operating projection M on the cam. d3 co-operates with The other end of the spring a member 35 rotatably mounted on the shaft It to bias this member in a'counter clockwise direction, as viewed in dotted lines in Fig. 3.

The operating element or arm 21 described above is preferably of U-shape with the pivot 28 at the end of one arm of the U and a pin 66 at the end oi the other arm of the U, the post 29 projecting downwardly described as ner, the operating element 21 is biased to the normal position shown in Fig. 3 when the contacts 2| and 25 are in engagement.

In operation of the switch, the contacts 2| and 25 are normally engaged since the operating arm 21 is biased in a counter-clockwise direction by the spring 63, and the cam 31 is biased in a clockwise direction so that the projection 1| thereon engages the stop 39, the actuating Handle I! being in the upper position shown in full lines in Fig. 1. As the handle I1 is moved downwardly to rotate the shaft It in a counter-clockwise direction, the cam 31 is also moved in a counter-clockwise direction against the bias of the spring 93, the spring 43 being further te sioned during this movement. Counter-clock- 31 forces the roller 38 and the operating element 21 downwardly causing the operating element to rotate in a clockwise direction around its pivot 28, causing further tensioning of the spring 43. clockwise rotation of the operating element21, the contacts 2| and 25 are disengaged with a wiping action, as hereinbefore described, and sub sequently the contacts 22 and 23are caused to engage, also-with a wiping action.

53 adjacent the cam 31 I from an intermediate portion of the U. The member 45, previously Upon sufiicient operating portion of the cam may Referring now more apropos It should here be noted that the amount of angular movement of the cam necessary to disengage the contacts 2| and 25 and then engage the contacts 22 and 26 is determined entirely by the shape of the operating edge of the cam 31. The engagement .and disengagement of the contacts may be made ciuite abrupt or slow relative to the angular movement of the cam. I prefer to make the slope of the cam operating surface away from its center of rotation quite abrupt angularqmovement of the actuating handle H.

fectir g'jhe movement of the operating element 21 in the zoperated position. In this manner, a desirable amount of over-travel of the cam is provided for, the limit of this over-travel being determined by the engagement of the projection 40 on the cam with thestop 39.- However, the be positioned at any point on the periphery of the cam to apportion over-travel asdesired.

specifically to the spring 43, the movement of the operating element 21 from the normal position to the operated position,

A end upon movement of shown in Fig. 4, serves to further tension the spring 43 since the engaged parts, namely the pin 46, the projection 41 on the member 45, and the end of the spring 43, all move downwardly as the operating element 21 moves to the operated position. Since the spring 43 is tensioned at each the actuating handle ill from the normal position to the operated position, upon release of the actuating handle H, the spring tension serves to rotate the cam 31 in the clockwise direction until the roller 38 on the opcrating element 21 reaches the abrupt slope on the cam. Thereupon, the operating element 21 is permitted to move upwardly under the bias of the spring 43 for disengaging the contacts 22 and 26 reengaging the contacts 2| and 25 in the normal position, shown in Fig. 3.

It should now be apparent that since all of the movable operating parts of the switch are eitherdirectly mounted on the demountable bearing plate IE or supported by. elements which are mounted thereon, the removal of the bearing plate from the casing l brings withit all 01' these operating parts. For factory assembly, the actuating handle l1, shaft I 4, the spring 43, the

N cam 31, the stop 42 and the remaining removable elements of the switch may be assembled on the bearing plate l and adjusted many modifications may be made, and I therefore contemplate by the appended claims to covenany such modifications as fall, within the true spirit and scope of my invention.

What I claim as new and desireito secure by Letters Patent of the United States is:

l. A controller comprising a stationary switch element, a movable switch element cooperating therewith, a member rotatable from a firstposition to a second position, a pivoted operating eleber for moving said movable switch element, said operating element moving from a first to a second position in accordance with a predetermined movement of said member, and a single spring simultaneously serving to bias said member and said operating element respectively to said first positions.

2. A controller comprising a stationary switch element, a movable switch element cooperating therewith, a member rotatable from a first position to a second position thereby, a pivoted operating element in camming relationship with said member for moving said movable switch element, said operating element moving from a first to a second position in accordance with a predetermined movement of said member, and a single helical spring simultaneously serving to bias said member and said operating element .respectively to said first positions, said spring being further tensioned by movement of said member from said first position toward said second position for returning said member and said operating element to their said respective first positions upon the release of said member.

3. A controller comprising a stationary switch element, a movable switch "element cooperating therewith, a rotatable actuating shaft, a cam carried by said shaft and rotatable from a first position to a second position thereby, a pivoted operating element operable from a first position to a second position by said cam in accordance with a predetermined movement thereof for moving said movable switch element, a single helical spring serving simultaneously to bias said cam and said operating element respectively to said first positions, said spring being tensioned by movement of said cam from said first position toward said second position for returning said cam and said operating element to their said respective first positions upon the release of said actuating shaft, and means limiting the rotation of said cam for determining said first and said second positions thereof.

4. A controller comprising a stationary switch element, a movable switch element cooperating ing said movable switch element, a single helical spring encircling said shaft and simultaneously serving to bias said cam and said operating element respectively to said first positions, 7 said spring being further tensioned by movement of said cam from said first position toward said second position for returning said cam and said operating element to their said respective first positions upon the release of said actuating shaft, said cam having a predetermined over-travel after operation of said operating element to said second position, and limiting means including a stop and a pair of p jections on said cam for determining said first nd said second positions of said cam.

5. A controller comprising a casing, a stationaryswitching element secured in said casing, a demountable bearing plate mounted on a wall of said casing, and operating means for said controllet in said casing, said operating means comprising a rotatable actuating shaft journaled in said bearing plate, a member carried by said shaft and rotatable from a. first position to a second posisaid movable switch element, said operating element moving from a first to a second position in accordance with a predetermined movement of said member, and spring means biasing said member and said operating element respectively to said first positions, said spring means being further tensioned by movement of said member from said first position toward said second position for returning said member and said operating element to their said respective first positions upon the release of said actuating shaft, said bearing plate and said operating means comprising a unitary structure readily removable from said casing without requiring disassembly of said unitary structure.

6. A controller comprising a casing, a stationary switching element secured in said, casing, a demountable bearing plate mounted on said casing, and operating means for said controller, said operating means comprising an actuating shaft journaled in said bearing plate and having a first portion extending into the interior of said casing and another portion accessible from the exterior thereof, a cam on said first portion of said shaft for rotation thereby from a first position to a second position, anoperating arm in said casing, a pivot for said arm onsaid bearing plate, a roller on said arm engaging said cam for moving said arm from a first position to a second position in accordance with a predetermined movement of said cam, spring means biasing said arm to said first position, and a movable switching element secured to said arm, said operating means and said bearing plate comprising a unitary structure readily removable from said casing without requiring disassembly of said unitary structure.

7. A controller comprising a stationary switch element, a movable switch element cooperating therewith, a rotatable actuating shaft, a cam associated with said shaft and rotatable from a first position to a second position thereby, a pivoted operating element operable from flfirst position to a second position by said cam in accordance with a predetermined movement thereof for moving said movable switch element, a helical spring encircling said shaft having one end biasing said cam and its other end biasing said operating element respectively to their said first positions, said helicalspring being further tensioned by movement of said cam from said first position toward said second position for returning said cam and said operating element to their said respective first positions upon the release of said actuating shaft, and limiting means including a stop and a pair of projections on said cam for engaging said stop to determine said first and said second positions of said cam.

8. A controller comprising a rotatable actuating shaft, a member on said shaft and rotatable from a first position to a second position thereby, a pivoted operating element in camming relationship with said member for movement thereby from a first position to a second position, spring means biasing said member and said operating element respectively to their said first positions, and switching means operable by said operating element including a relatively fixed contact and a movable contact for engagement therewith, a main support for said movable contact, said main support being mounted on said operating element and having a portion extending transversely of the line of movement of saidmovable contact, a spring, means confining said spring under compression, an auxiliary support for said movable contact having a portion supported by said main support and extending transversely thereof, said portion of said auxiliary support being positioned between an end of said spring and said confining means and held under the bias of said spring, said auxiliary support having a further portion extending transversely of said line of movement of said movable contact for mounting said movable contact to provide a leverage for pivoting or rocking said auxiliary support upon engagement of said contacts, said auxiliary support being loosely mounted on said main support for pivotal movement on said confining means to provide a wiping engagement of said contacts.

9. A controller comprising a rotatable actuating shaft, a member secured to said shaft and rotatable from a first position to a second position thereby, a pivoted operating element in camming relationship with said member for movement thereby from a first position to a second position, spring means biasing said member and said operating element respectively to their said first positions, and switching means operable by said operating element including a relatively fixed contact and a movable'contact for engagement therewith, a main support for said movable contact, said main support being mounted on said operating element and having a portion extending transversely of the line of movement of said movable contact, a helical spring encircling said transversely extending portion of said main support, means disposed at each end of said spring confining it under compression, an auxiliary support for said movable contact having a portion normally positioned at substantially right angles to the axial line of said spring and disposed between an end of said spring and said confining means, said auxiliary support having a further portion extending transversely of said line of movement of said movable contact for mounting said movable contact to provide a leverage for rocking or pivoting said auxiliary support upon engagement of said contacts, said auxiliary support being loosely mounted on said main support for pivotal movement on said confining means to provide a wiping engagement of said contacts.

10. A controller comprising a rotatable actuating shaft, a member secured to said shaft and rotatable from a first position to a second position thereby, a pivoted operating element in camming relationship with said member for movement thereby from a first position to a second position, spring means biasing said member and said operating element respectively to their said first positions, said spring means being further tensioned by movement of said member from said first position toward said second position for returning said member and said operating element to their said respective first positions upon release of said actuating shaft, and switching means operable by said operating element ino cluding a relatively fixed contact and a movable contact for engagement therewith, a3main support for said movable contact, said main support being mountedon said operating element and having a portion extending transversely of the line of movement of said movable contact, a helical spring encircling said transversely extending portion of said main support, means disposed at each end of said spring confining it under compression, an auxiliary support for said movable contact having a portion normally positioned at substantially right angles to the axial line of said spring and disposed between an end of said spring and said confining means, said auxiliary support having a further portion extending transversely of said line of movement of said movable contact for mounting said movable contact to provide a leverage for rocking or pivoting said auxiliary support upon engagement of said contacts, said auxiliary support being loosely mounted on said main support for pivotal move ment on said confining means to provide a wiping engagement of said contacts.

11. The combination witha controller having an operating element of switching means for said controller operable by said operating element inincluding a relatively fixed contact and a movable contact for engagement therewith, a main support for said movable contact, said main support being mounted on said operating element and having a portion extending transversely of the line of movement of said movable contact, a spring, means confining said spring under compression, an auxiliary support for said movable contact having a portion supported by said main support and extending transversely thereof, said portion of said auxiliary supp rt being positioned between an end of said spring and said confining means and held under the bias of said spring, said auxiliary support having a further portion extending transversely of said line of movement of said movable contact and associated with said movable contact to provide a leverage for pivoting or rocking said auxiliary support upon engagement of said contacts, said auxiliary support being loosely mounted on said main support for pivotal movement on said confining means to provide a wiping engagement of said contacts.

12. The combination with a controller having an operating element of switching means for said controller operable by said operating element including a relatively fixed contact and a movable.

contact for engagement therewith, a main support-for said movable contact, said main support being mounted on said operating element and having a portion extending transversely of the line or movement of said movable contact, a helical spring encircling said transversely extending portion of said'main support, means disposed at each end of said spring confining it under compression, an auxiliary support for said movable contact having a portion normally positioned at substantially right angles to the axial line of said spring and disposed between an end of said spring and said combining means, said auxiliary support having a further portion extending transverselyof said line of movement of said movable contact for mounting said movable contact to provide a leverage for rocking or pivoting saidauxiliary support upon engagement of said contacts, said auxiliary support being loosely mounted on said main support for pivotal movement on said confining means to provide a wiping engagement of said contacts.

13. An electric switch comprising a cam, means mounting said cam for rotation about a predetermined axis, an actuating -member pivotally mounted for movement about an axis substantially parallel with said first axis but spaced therefrom, a spring operatively associated with said cam and said actuating member respectively for biasing said actuating member about its axis into engagement with said cam and for biasing said cam and said actuating member in opposite directions about their respective axes to predetermined relative first positions, said cam being shaped to turn said actuating member about its axis when said cam is turned from said first position, and circuit control means actuated by movement of said actuating member.

14. An electric switch comprising a. cam, a shaft mounting said cam for rotation about a predetermined axis, an actuating member pivotally mounted for movement about an axis substantially parallel with said first axis but spacedv 

